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MM: Fachverband Metall- und Materialphysik

MM 12: Computational Materials Modelling - Mechanical Properties

MM 12.4: Talk

Monday, March 11, 2013, 16:30–16:45, H24

Atomistic modelling of α-Fe and Fe-C by analytic bond-order potentials including magnetism — •Sebastian Schreiber, Thomas Hammerschmidt, and Ralf Drautz — ICAMS, Ruhr-Universität Bochum

The mechanical properties of steels are to a large degree determined by plastic deformations on the microstructural level. Understanding the involved processes at such length-scales calls for atomistic simulations of the movement of line defects. This may help to explain, e.g., the influence of temperature and carbon content on dislocation glide in α-Fe and to make direct contact to recent atom-probe experiments. However, simulating the interaction of dislocations and other defects with atomic resolution requires computationally efficient methods that are able to treat million-atom simulation cells. To this end, we develop analytic Bond-Order potentials (BOP) that are footed on recently parametrised tight-binding (TB) models of Fe and Fe-C. The analytic BOP provide an approximate solution to the TB problem and include the treatment of magnetism within the Stoner model. Here, we demonstrate the transferability of taking the Fe and Fe-C TB parameters to the analytic BOP formalism and discuss first results of large scale BOP simulations that will lead us to the calculation of the Peierls stress for dislocation movement. Moreover, we will present benchmarks of the computational performance of the analytic BOP with respect to system size and parallelisation.